Water and Desalination

A recent conference on water at MIT brought some interesting concepts around water in the middle east into better focus. 

1. The cost of transportation cannot be ignored.  For example, the nominal cost of desalinated water on the Israeli coast is $0.60/ton.  The cost of transporting water from the central hills to Gaza is $0.40.  So there is no point in Gaza paying more than $0.20 for a ton of water from the hills.  The speaker argues that this reality makes water wars more hype than reality.  People may use water as an excuse, but most of the situations don't involve enough money to justify a war.  The available capacity in the hills is 100 million tons/yr.  So after all the emotional rhetoric is done, arguments about that water are arguments over $20 million.  That's all it's worth.
2. Another speaker pointed out that the nominal number was from 2010.  The actual cost for desalinated water is presently $0.50, and it's falling.  So the arguments are over even smaller amounts of money.
3. Transportation limits are also important.  Amman gets its water from the Jordan river.  Alongside the river, water is about $0.15/ton.  In Amman it's as much as $2.00/ton during dry periods.  It climbs very rapidly in cost as demand increases.  This is because the pipelines between the Jordan river valley and Amman are usually running at near full capacity.  The alternatives are limited, so during scarcity the price climbs dramatically.  That high price mostly serves to eliminate forms of water use.

Equally interesting, after about 25 years of discussion, Israel, Jordan, and Palestine have finally reached an agreement on the Red Sea - Dead Sea project.  It's only agreement to proceed past the preliminary stage, but there is significant economic pressure to keep moving.  The concept is simple.  Sea water will be taken from the Red Sea, and used to generate hydro power (using the 400m drop down to the Dead Sea) which is used to desalinate the water.  The resulting waste brine is dumped into the Dead Sea.  They've agreed to examine two plans, both sharing the same locations for hydro-power, desalination, canals, and pipelines.  One plan takes full capacity sea water from the start, dumping the excess into the Dead Sea.  The other plan increases the water flow as desalination plants come on line.  It dumps only concentrated brine into the Dead Sea.

The project includes a pipeline to Amman, which deals with their skyrocketing water costs during high demand.  It's less clear how it would affect the water extraction in the Jordan river valley.

Update: I did the arithmetic on energy requirements.  The potential energy of one ton with a 400m drop is about 1.2 Kwh.  The chemical energy of salt mixed in 1 ton of sea water is just under 1 Kwh.  Hydro energy conversion is not 100% efficient, and desalination is not 100% energy efficient, so there isn't enough potential energy to do full desalination without outside energy sources.  Further, much of the fresh water will be left at a high elevation so that it can be sent into Jordan.  So this scheme probably needs further outside power sources.  The brine goes all the way down allowing full energy recovery.  The lower percentage fresh water per ton of sea water reduces the chemical energy needed.  That's probably not enough for the system to be fully self-powering.